We have previously described a process for the production of a high lysine yeast (HLY). HLY is greater than 90% available to meet the lysine requirement of rats fed a wheat gluten diet. But there is controversy concerning the need for lysine supplementation of wheat products in adults and growing children. Certain evidence that rats can adapt to diets limiting in lysine will be repeated and extended to obtain baseline data that may relate to the situation in man. Rats grown on cereal grain diets limiting in lysine or threonine will be sacrificed weekly, and levels of catabolic enzymes of lysine and threonine metabolism, lysine and threonine in the serum and tissue, and 3-methylhistidine in the serum (as a measure of protein catabolism) determined. Work will continue on the biosynthesis of slaframine, l-acetoxy-6-aminooctahydro-indolizine (SF) and a 1-pyrindine alkaloid deriving from lysine in Rhizoctonia leguminicola. A previously unrecognized metabolite (M) of pipecolate metabolism accumulates in this mold under vigorous aeration, conditions that limit SF production. Chemical studies indicate M may be related to intermediates of SE biosynthesis; isolation and characterization of M are in progress: Radioactive SF is formed following incubation of R. leguminicola mycelium with 2-C14 malonate; and a pipecolate dependent decarboxylation of malonate can be demonstrated in crude mold extracts. Pipecolate dependent decarboxylation of malonate can be demonstrated in crude mold extracts. Pipecolate and malonate may condense to give a product (X) which on decarboxylation and cyclization could form either the octahydroindolizine or pyrindine ring systems. Work will focus on improving enzymatic conditions favoring accumulation of X such that it might be characterized and its role in the biosynthesis of the piperidine alkaloids of this mold elucidated. Attempts will be made to synthesize compounds implied by the malonate hypothesis and then tested for biological activity. BIBLIOGRAPHIC REFERENCES: Broquist, H.P. Production and Nutritional Properties of a High Lysine Yeast. Fifth Biennial Symposium of Biochemistry and Nutrition, Pahlavi University, Shiraz, Iran, May 5-7, 1975. Broquist, H.P., Role of Lysine in Carnitine Biosynthesis. Xth International Congress of Nutrition, Kyoto, Japan, Aug. 3 - 9, 1975.